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Aerosols such as this smog over Mexico City have helped keep temperatures down. What would happen if they were cleaned up? Flickr/brian.gratwicke

Ten days: how we imagine climate change

This decade has been called the “critical decade” for action on climate change. Decisions that we make in the years up to 2020 will determine the severity of climate change, and the impact it will have on society.

But communicating the urgency of climate change has proved problematic, for two reasons. First, the very existence of climate change has been regressively reconstructed as a pseudo “debate” in much of our mainstream media, and secondly, those who live in cities are so sheltered from its reality.

Second, imagining climate change is so difficult for those who live in cities. We are disconnected from experiencing it by our built and virtual environments. Our cars, our homes, climate control, the private comforts that we take for granted, allow us to bunker-in and not have to worry about what even the weather is doing, let alone climate.

Our culture of speed and “instantaneous time” also makes it difficult to imagine the incremental reality of climate change. Increasingly we are time-poor, living in a perpetual present which demands that we forever accelerate our behaviour. Speed is equated with efficiency, and our busy-ness demands that we should “find” time for leisure.

Unless you are a gardener, instantaneous time makes it so much harder for city people to imagine climate change, unlike people who live on the land, or by the oceans, or are from cultures with strong memories of the past. For these people, even small changes, like shortening seasons or climate shifting polewards along with species of fish, plants and insects are more likely to be noticed.

But for people, urban and rural, more imperceptible is a paradox that is at the core of dangerous climate change.

It is that, at any given moment, the magnitude of climate change is greatly under-estimated. This is because of the industrial emissions of aerosol particles – a human-made “albedo” which reflects solar radiation away from the earth.

Just how much these aerosols (as opposed to natural albedo like reflective icesheets, glaciers and volcanic ash) are masking the warming that would otherwise be happening isn’t entirely known yet. Complicating the forecasts is that albedo aerosols co-exist with black aerosols, such as diesel emissions which increase global warming.

A satellite mission designed to measure albedo, known as the “glory mission” failed to reach its orbit in 2011, and NASA has not been able to follow it up since. In the meantime, forecasting based on observation is still very accurate, but what we don’t know precisely is how much more warming we would get without the aerosols.

Fossil fuels may emit CO2, but they also emit aerosols. Flickr/Jamie_Potter

Estimates based on a combination of scanning, and meteorological laboratory tests suggests the influence could be as much as 50% mitigation.

So herein lies the problem. Let’s suppose all emissions were to stop tomorrow … what would happen?

According to a 2009 peer-reviewed paper on carbon residence times by leading climate researchers, global warming would continue to increase because current levels of CO2 will stay in the atmosphere for hundreds of years, even with the ability of plants to recover much of that carbon.

The residence time of the carbon has already committed us to warming approaching 2C, which would certainly be surpassed if greenhouse gases continue at current or greater levels.

But here’s the twist.

If all emissions were to stop tomorrow, so would the output of those human-made aerosols reflecting radiation back into space. These aerosols have a residence time in the atmosphere of just ten days, meaning that after just ten days it would be like increasing CO2 emissions by 50%. It kind of makes reducing CO2 emissions to 5% off 2000 levels by 2020 seem rather pathetic.

Ten days, a time-horizon that people in the city should be able to relate to.

If this were to happen, the likelihood of the positive feedbacks that are triggered by warming, such as more abundant water vapour, natural albedo loss (like melting ice an glaciers), extensive firestorms, and methane pulses, would be greatly enhanced.

Because current carbon policies are ignoring aerosols and the effect they have, targets may be dangerously ineffective. Much more urgent and radical targets are needed to avoid dangerous climate change, as even radical targets will still require a period of quite harsh adaptation as the planet sweats out the effects of unmasked CO2 already “in the pipeline”. If we subtract the masking effect of aerosol we must face up to the fact we may already be committed to 2C.

Right now is the critical decade for action, followed by many more decades of trying to live with what we have done.

This article is the final of three articles on how we imagine climate change. The first two are here and here

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